The names of all the New York victims are being read out
Americans are holding ceremonies to mark the sixth anniversary of the 9/11 attacks on the US.
Nearly 3,000 people were killed when four planes were hijacked and flown into New York's World Trade Center, the Pentagon and a field in Pennsylvania.

Church bells tolled at 0846 local time to mark the moment when the first Trade Center tower was hit.

A message purportedly from al-Qaeda head Osama Bin Laden has been released, praising one of the hijackers.

'Remembrance and renewal'

For the first time, much of the New York ceremony is taking place away from the World Trade Center site - known as Ground Zero - because of construction there.

The enemies of America, the enemies of our values and our liberty, will never again rest easy

Defence Secretary Robert Gates

9/11: The four hijacks
In graphics: How towers fell
In pictures: 9/11 anniversary

Those taking part have gathered at a nearby park instead, to a backdrop of bagpipes, drum beats and overcast skies.

The names of the New York victims were being read out as in previous years but for the first time by the surviving firefighters and other emergency workers on duty at the time.

Some of those reading out the names were overcome with emotion as they came to list fallen colleagues.

Much of the New York ceremony is taking place away from Ground Zero

The ceremony includes two pauses to mark the moments when the two planes crashed into the twin towers, and two more to mark the moments when the buildings collapsed.

Relatives of the 2,749 people killed in New York by 10 of the hijackers will be able to file down a ramp into the World Trade Center site to lay flowers.

New York's Mayor Michael Bloomberg told the families: "Six years have passed and our place is still by your side."

Rudy Giuliani, the city's mayor on 11 September 2001, has attracted criticism for using his performance in the weeks after the attacks in his campaign to be the Republican Party's presidential nominee.

He said his appearance at the ceremony was not intended to be political.

'Shared sorrow'

President George W Bush, who in past years has laid a wreath at the site and made a speech, observed a moment of silence at the White House.

Defence Secretary Robert Gates hosted a memorial service at the Pentagon for relatives of the 184 people killed by the five hijackers aboard American Airlines flight 77.

He paid tribute to those killed and spoke of the nation's shared sorrow and pain at their loss.

Mr Gates also vowed to defend the American people and their values from any threat.

"The enemies of America, the enemies of our values and our liberty, will never again rest easy because we will hunt them down relentlessly and without reservation," he said.

A further ceremony was being held in Shanksville, Pennsylvania, where United Airlines flight 93 crashed after some of the 40 passengers and crew rushed the four men who hijacked that plane.

A memorial event was also held at the main US airbase in Afghanistan.

Hijacker's voice

A new message purported to be from Bin Laden has been released to coincide with the anniversary.

Bin Laden's new message praises a 9/11 hijacker
In it, a still photograph of the al-Qaeda leader is shown while his voice is heard praising the role of Waleed al-Shehri, one of the 19 hijackers.

It comes just a few days after the release of Bin Laden's first video for three years.

In the new message he wears the same beige cloak and dark trimmed beard as in last week's video.

The new video also shows footage of al-Shehri, recorded shortly before his death, speaking about what motivated him to help hijack American Airlines flight 11, the first of the planes flown into the twin towers.

This is the sixth video released by al-Qaeda featuring the hijackers.

BBC security correspondent Gordon Corera says it is part of a regular cycle of al-Qaeda releasing videos to coincide with the 9/11 anniversary.